The interplay of interleukin-10 (IL-10) and interleukin-2 (IL-2) in humoral immune responses: IL-10 synergizes with IL-2 to enhance responses of human B lymphocytes in a mechanism which is different from upregulation of CD25 expression

Influence of occlusal loading on peri-implant inflammatory cytokines in crevicular fluid: a prospective longitudinal study

Objective

The objective of the study was to evaluate the relation between occlusal loading and peri-implant crevicular fluid cytokine expression in patients with implant-supported complete fixed prostheses in both arches.

Material and methods

A prospective longitudinal clinical study was performed at a university clinic. Fifteen patients were selected and 11 were included. All patients had bimaxillary implant-supported complete fixed ceramo-metallic prostheses loaded at least 12 months before the beginning of the study. Allocation was established for each patient using a computerized occlusal analysis system. The test implant was the maxillary implant closest to the point of highest occlusal loading. The maxillary implant with least loading was the control implant. Occlusal adjustment was performed using a round diamond burr. This occlusal distribution was verified with the occlusal analysis system. Expression of cytokines from peri-implant crevicular fluid (TNF-α, IL-10, IL-6, IL-1β, IL-8) were recorded and analyzed in both test and control implants before (baseline: T0) and 2 (T1) and 12 months (T2) after occlusal adjustment. The Brunner-Langer non-parametric test was performed.

Results

At T0, the expression of IL-10 was significantly higher in the test group implants (p = 0.018). Between T0 and T1, the expression of all the cytokines decreased in the implants of both groups with statistically significant differences, except for TNF (p = 0.271). When comparing both groups at T1, there was no statistically significant difference in any of the analyzed cytokines. At T2, TNF-α suffered when compared with baseline, a statistical decrease in both study and control implants (p < 0,001). At T2, there were no statistically significant differences between groups in any of the cytokines analyzed.

Conclusions

Implants with higher occlusal load presented higher expression of IL-10 in peri-implant crevicular fluid. Occlusal adjustment produced a decrease in the expression of all the analyzed cytokines, both in test and control implants.

Multi-parametric flow cytometric and genetic investigation of the peripheral B cell compartment in human type 1 diabetes

The appearance of circulating islet-specific autoantibodies before disease diagnosis is a hallmark of human type 1 diabetes (T1D), and suggests a role for B cells in the pathogenesis of the disease. Alterations in the peripheral B cell compartment have been reported in T1D patients; however, to date, such studies have produced conflicting results and have been limited by sample size. In this study, we have performed a detailed characterization of the B cell compartment in T1D patients (n = 45) and healthy controls (n = 46), and assessed the secretion of the anti-inflammatory cytokine interleukin (IL)-10 in purified B cells from the same donors. Overall, we found no evidence for a profound alteration of the B cell compartment or in the production of IL-10 in peripheral blood of T1D patients. We also investigated age-related changes in peripheral B cell subsets and confirmed the sharp decrease with age of transitional CD19(+) CD27(-) CD24(hi) CD38(hi) B cells, a subset that has recently been ascribed a putative regulatory function. Genetic analysis of the B cell compartment revealed evidence for association of the IL2-IL21 T1D locus with IL-10 production by both memory B cells (P = 6·4 × 10(-4) ) and islet-specific CD4(+) T cells (P = 2·9 × 10(-3) ). In contrast to previous reports, we found no evidence for an alteration of the B cell compartment in healthy individuals homozygous for the non-synonymous PTPN22 Trp(620) T1D risk allele (rs2476601; Arg(620) Trp). The IL2-IL21 association we have identified, if confirmed, suggests a novel role for B cells in T1D pathogenesis through the production of IL-10, and reinforces the importance of IL-10 production by autoreactive CD4(+) T cells.

Cytokine-Mediated Regulation of Plasma Cell Generation: IL-21 Takes Center Stage

During our life, we are surrounded by continuous threats from a diverse range of invading pathogens. Our immune system has evolved multiple mechanisms to efficiently deal with these threats so as to prevent them from causing disease. Terminal differentiation of mature B cells into plasma cells (PC) – the antibody (Ab) secreting cells of the immune system – is critical for the generation of protective and long-lived humoral immune responses. Indeed, efficient production of antigen (Ag)-specific Ab by activated B cells underlies the success of most currently available vaccines. The mature B-cell pool is composed of several subsets, distinguished from one according to size, surface marker expression, location, and Ag exposure, and they all have the capacity to differentiate into PCs. For a B-cell to acquire the capacity to produce Abs, it must undergo an extensive differentiation process driven by changes in gene expression. Two broad categories of Ags exist that cause B-cell activation and differentiation: T cell dependent (TD) or T cell independent (TI). In addition to the B-cell subset and nature of the Ag, it is important to consider the cytokine environment that can also influence how B-cell differentiation is achieved. Thus, while many cytokines can induce Ab-secretion by B cells after activation with mimics of TD and TI stimuli in vitro, they can have different efficacies and specificities, and can often preferentially induce production of one particular Ig isotype over another. Here, we will provide an overview of in vitro studies (mouse and human origin) that evaluated the role of different cytokines in inducing the differentiation of distinct B-cell subsets to the PC lineage. We will place particular emphasis on IL-21, which has emerged as the most potent inducer of terminal B-cell differentiation in humans. We will also focus on the role of IL-21 and defects in B-cell function and how these contribute to human immunopathologies such as primary immunodeficiencies and B-cell mediated autoimmune conditions.

Rosmarinic acid-rich extracts of summer savory (Satureja hortensis L.) protect Jurkat T cells against oxidative stress

Summer savory (Satureja hortensis L., Lamiaceae) is used in several regions of the world as a spice and folk medicine. Anti-inflammatory and cytoprotective effects of S. hortensis and of its rosmarinic acid-rich phenolic fraction have been demonstrated in animal trials. However, previous studies of rosmarinic acid in cell models have yielded controversial results. In this study, we investigated the effects of summer savory extracts on H2O2-challenged human lymphoblastoid Jurkat T cells. LC-MS analysis confirmed the presence of rosmarinic acid and flavonoids such as hesperidin and naringin in the phenolic fraction. Adding 25 or 50 µM of H2O2 to the cell culture caused oxidative stress, manifested as generation of superoxide and peroxyl radicals, reduced cell viability, G0/G1 arrest, and enhanced apoptosis. This stress was significantly alleviated by the ethanolic and aqueous extracts of S. hortensis and by the partially purified rosmarinic acid fraction. The application of an aqueous S. hortensis extract doubled the activity of catalase and superoxide dismutase in the cells. The production of IL-2 and IL-10 interleukins was stimulated by H2O2 and was further enhanced by the addition of the S. hortensis extract or rosmarinic acid fraction. The H2O2-challenged Jurkat cells may serve as a model for investigating cellular mechanisms of cytoprotective phytonutrient effects.

B cell receptor-ERK1/2 signal cancels PAX5-dependent repression of BLIMP1 through PAX5 phosphorylation: a mechanism of antigen-triggering plasma cell differentiation

Plasma cell differentiation is initiated by Ag stimulation of BCR. Until BCR stimulation, B lymphocyte-induced maturation protein 1 (BLIMP1), a master regulator of plasma cell differentiation, is suppressed by PAX5, which is a key transcriptional repressor for maintaining B cell identity. After BCR stimulation, upregulation of BLIMP1 and subsequent suppression of PAX5 by BLIMP1 are observed and thought to be the trigger of plasma cell differentiation; however, the trigger that derepresses BLIMP1 expression is yet to be revealed. In this study, we demonstrated PAX5 phosphorylation by ERK1/2, the main component of the BCR signal. Transcriptional repression on BLIMP1 promoter by PAX5 was canceled by PAX5 phosphorylation. BCR stimulation induced ERK1/2 activation, phosphorylation of endogenous PAX5, and upregulation of BLIMP1 mRNA expression in B cells. These phenomena were inhibited by MEK1 inhibitor or the phosphorylation-defective mutation of PAX5. These data imply that PAX5 phosphorylation by the BCR signal is the initial event in plasma cell differentiation.

Visible light promotes interleukin-10 secretion by sublethal fluences

OBJECTIVE

To determine the effect of blue light on cultured splenocyte viability and secretion of cytokines involved in the regulation of immune responses in the inflammatory process.

BACKGROUND DATA

Previous studies showed that red light has various effects on lymphocyte proliferation and production of cytokines.

MATERIALS AND METHODS

Cultured mouse splenocytes were exposed to visible light (wavelengths, 450-490 nm) using 2-108 J/cm(2), with and without scavengers of reactive oxygen species (ROS). One half of the samples were stimulated by the heat-killed periopathogenic bacterium Porphyromonas gingivalis. Following incubation for 48 h, the levels of the cytokines interleukin-10 (IL-10), tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) were analyzed, and the viability of the cells was tested using the XTT assay. The total oxidant-scavenging capacity of the nonexposed and exposed splenocytes to light was determined by a chemiluminescence assay, and the temperature of the cell culture medium was measured after light exposure.

RESULTS

Exposure to blue light at fluences of 27-108 J/cm(2) caused a decrease in splenocyte viability. Lower fluences increased the secretion of cytokine IL-10, which was abolished by ROS scavengers. Exposure to light had no effect on the secretion of cytokines TNFα and IFNγ. Following exposure to light, more ROS were detected and the temperature measured did not exceed 30.7°C.

CONCLUSIONS

Blue light had a stimulatory effect on cell secretion of IL-10, mediated by ROS. Therefore, an increase in IL-10 might be a potential method for modulating the inflammatory processes of local disorders, such as periodontitis and arthritis.

Genome-wide analysis of immune activation in human T and B cells reveals distinct classes of alternatively spliced genes

Alternative splicing of pre-mRNA is a mechanism that increases the protein diversity of a single gene by differential exon inclusion/exclusion during post-transcriptional processing. While alternative splicing is established to occur during lymphocyte activation, little is known about the role it plays during the immune response. Our study is among the first reports of a systematic genome-wide analysis of activated human T and B lymphocytes using whole exon DNA microarrays integrating alternative splicing and differential gene expression. Purified human CD2⁺ T or CD19⁺ B cells were activated using protocols to model the early events in post-transplant allograft immunity and sampled as a function of time during the process of immune activation. Here we show that 3 distinct classes of alternatively spliced and/or differentially expressed genes change in an ordered manner as a function of immune activation. We mapped our results to function-based canonical pathways and demonstrated that some are populated by only one class of genes, like integrin signaling, while other pathways, such as purine metabolism and T cell receptor signaling, are populated by all three classes of genes. Our studies augment the current view of T and B cell activation in immunity that has been based exclusively upon differential gene expression by providing evidence for a large number of molecular networks populated as a function of time and activation by alternatively spliced genes, many of which are constitutively expressed.

Essential role of IL-21 in B cell activation, expansion, and plasma cell generation during CD4+ T cell-B cell collaboration

During T cell-B cell collaboration, plasma cell (PC) differentiation and Ig production are known to require T cell-derived soluble factors. However, the exact nature of the cytokines produced by activated T cells that costimulate PC differentiation is not clear. Previously, we reported that costimulation of purified human B cells with IL-21 and anti-CD40 resulted in efficient PC differentiation. In this study, we addressed whether de novo production of IL-21 was involved in direct T cell-induced B cell activation, proliferation, and PC differentiation. We found that activated human peripheral blood CD4(+) T cells expressed mRNA for a number of cytokines, including IL-21, which was confirmed at the protein level. Using a panel of reagents that specifically neutralize cytokine activity, we addressed which cytokines are essential for B cell activation and PC differentiation induced by anti-CD3-activated T cells. Strikingly, neutralization of IL-21 with an IL-21R fusion protein (IL-21R-Fc) significantly inhibited T cell-induced B cell activation, proliferation, PC differentiation, and Ig production. Inhibition of PC differentiation was observed even when the addition of IL-21R-Fc was delayed until after initial B cell activation and expansion had occurred. Importantly, IL-21 was found to be involved in PC differentiation from both naive and memory B cells. Finally, IL-21R-Fc did not inhibit anti-CD3-induced CD4(+) T cell activation, but rather directly blocked T cell-induced B cell activation and PC differentiation. These data are the first to document that B cell activation, expansion, and PC differentiation induced by direct interaction of B cells with activated T cells requires IL-21.

IL-10 gene transfer attenuates P. gingivalis-induced inflammation

IL-10 is an anti-inflammatory cytokine secreted by stimulated Th2 lymphocytes that can down-regulate inflammatory responses to bacterial challenge. We hypothesized that local delivery of IL-10 using gene-transfer will down-regulate inflammatory responses. We examined the effect of IL-10 plasmid injection on the local cytokine response. Two weeks after the implantation of chambers, either IL-10 plasmid or vector was injected into the mice. Four days later, they were challenged with an intra-chamber injection of P. gingivalis. The intra-chamber levels of IL-10, IFNgamma, TNFalpha, and IL-1beta were evaluated after 2 and 24 hrs. The results showed that local IL-10 gene delivery elevated the levels of IL-10 at both time periods. It attenuated the levels of IFNgamma (656 +/- 154 to 218 +/- 144 pg/mL) and TNFalpha (23 +/- 2.0 to 12.5 +/- 2.9 ng/mL) at 2 hrs, and of IL-1beta (21.5 +/- 5.7 to 12.4 +/- 3.0 ng/mL) at 24 hrs. The results suggest the possibility of modulating the local inflammatory response to P. gingivalis by direct IL-10 gene transfer.

Effect of cyclophosphamide and 61.22 GHz millimeter waves on T-cell, B-cell, and macrophage functions

The present study was undertaken to investigate whether millimeter waves (MMWs) at 61.22 GHz can modulate the effect of cyclophosphamide (CPA), an anti-cancer drug, on the immune functions of mice. During the exposure each mouse's nose was placed in front of the center of the antenna aperture (1.5 x 1.5 cm) of MMW generator. The device produced 61.22 +/- 0.2 GHz wave radiation. Spatial peak Specific Absorption Rate (SAR) at the skin surface and spatial peak incident power density were measured as 885 +/- 100 W/kg and 31 +/- 5 mW/cm(2), respectively. Duration of the exposure was 30 min each day for 3 consecutive days. The maximum temperature elevation at the tip of the nose, measured at the end of 30 min, was 1 degrees C. CPA injection (100 mg/kg) was given intraperitoneally on the second day of exposure to MMWs. The animals were sacrificed 2, 5, and 7 days after CPA administration. MMW exposure caused upregulation in tumor necrosis factor-alpha (TNF-alpha) production in peritoneal macrophages suppressed by CPA administration. MMWs also caused a significant increase in interferon-gamma (IFN-gamma) production by splenocytes and enhanced proliferative activity of T-cells. Conversely, no changes were observed in interleukin-10 (IL-10) level and B-cell proliferation. These results suggest that MMWs accelerate the recovery process selectively through a T-cell-mediated immune response.

Accelerated alveolar bone loss in mice lacking interleukin-10

Interleukin-10 regulates pro-inflammatory cytokines, including those implicated in alveolar bone resorption. We hypothesized that lack of interleukin-10 leads to increased alveolar bone resorption. Male interleukin-10(-/-) mice, on 129/SvEv and C57BL/6J background, were compared with age-, sex-, and strain-matched interleukin-10(+/+) controls for alveolar bone loss. Immunoblotting was used for analysis of serum reactivity against bacteria associated with colitis and periodontitis. Interleukin-10(-/-) mice had significantly greater alveolar bone loss than interleukin-10(+/+) mice (p = 0.006). The 30-40% greater alveolar bone loss in interleukin-10(-/-) mice was evident in both strains, with C57BL/6J interleukin-10(-/-) mice exhibiting the most bone loss. Immunoblotting revealed distinct interleukin-10(-/-) serum reactivity against Bacteroides vulgatus, B. fragilis, Prevotella intermedia, and, to a lesser extent, against B. forsythus. The results of the present study suggest that lack of interleukin-10 leads to accelerated alveolar bone loss.

The Echinococcus multilocularis 14-3-3 protein protects mice against primary but not secondary alveolar echinococcosis

Alveolar echinococcosis (AE), caused by the larval stage (metacestode) of the tapeworm Echinococcus multilocularis, exhibits very similar disease characteristics in humans and rodents. Recently, it has been shown that an over-expression of the parasite 14-3-3 protein could be associated to the proliferative growth of the E. multilocularis metacestode. We now demonstrate the expression of this protein at the E. multilocularis oncospheral stage as well. A recombinant E. multilocularis 14-3-3 protein (E14t) was used to vaccinate mice against either primary or secondary experimental E. multilocularis infection in BALB/c mice. Conversely to non-vaccinated but control infected mice, which developed a very weak anti-E14t response during infection, the response elicited in the E14t-vaccinated and subsequently infected animals exhibited a strong reactivity against the parasite 14-3-3 protein. Major differences became apparent between secondarily and primarily infected animals: whereas no protection against secondary infection was achieved by vaccination, vaccinated animals were protected by 97% against challenge primary infection with 2000 E. multilocularis eggs. Consequently, the parasite 14-3-3 molecule appears crucially involved in the early stage of the host-parasite interplay and exhibits potential to be used as target molecule for the development of protective tools against AE.

Interferon-beta therapy in multiple sclerosis: evidence for a clinically relevant dose response

There have been considerable advances made recently in the treatment of multiple sclerosis (MS). In particular, interferon (IFN)beta has been demonstrated in several independent, multicentre clinical trials to lower unequivocally the biological activity of this illness. The results of these trials have been remarkably consistent, demonstrating a reduction in both disease activity and cumulative disability, using a combination of clinical and magnetic resonance imaging outcome measures. Nevertheless, the importance of the total weekly IFNbeta dose in the clinical management of individual patients has been controversial. However, there is considerable information available regarding the effect of IFNbeta dose on the various biochemical and clinical markers that are affected by IFNbeta, which is derived both from pre-clinical studies and multicentre clinical trials. On balance, convincing evidence is provided to support the notion that there is a clinically relevant dose-response in the use of IFNbeta to treat patients with relapsing/remitting MS. However, many of the clinical trials of IFNbeta in MS have confounded the potential effects of dose with the possible effects of frequency of IFNbeta administration. As a result, it is possible that the apparent dose-response observed in these clinical trials may be due, in part, to the more frequent dose administration schedule rather than the total weekly dose.

Deficient interleukin-10 production by neonatal T cells does not explain their ineffectiveness at promoting neonatal B cell differentiation

Neonatal T cells are poor promoters of Ig secretion by neonatal B cells. Since IL-10 has been shown to play a role in B cell differentiation, we investigated the relationship of IL-10 production by neonatal T cells and their ability to provide B cell help. Neonatal CD4+(CD8-) T cells and adult naive CD4+ (CD8-/CD45RO-) T cells activated with immobilized anti-CD3 produced consistently less IL-10 than adult memory CD4+(CD8-/CD45RA-) T cells. Production of IL-10 by adult and neonatal T cells was dependent on IL-2, but was unaffected by supplemental IL-4. Despite diminished IL-10 production, supplemental IL-10 increased neonatal T cell-dependent Ig secretion only modestly, but did not increase Ig heavy chain isotype switching. This contrasted with the ability of IL-10 to enhance the secretion of all Ig isotypes by adult B cells stimulated in the presence of either IL-2 or IL-4. These results suggest that IL-10 can promote T cell-dependent Ig secretion but not Ig heavy chain isotype switching by neonatal B cells. However, deficient IL-10 production alone does not account for the poor ability of neonatal T cells to support neonatal B cell Ig production.

IL-10 gene transfer to intracranial 9L glioma: tumor inhibition and cooperation with IL-2

This study examines the effects of interleukin-10 (IL-10) and combination IL-10 + IL-2 gene transfer on experimental brain tumor growth in vivo. 9L gliosarcoma cells were engineered to stably express murine IL-10 (9L-IL-10 cells) and implanted subcutaneously or to the caudate/putamen of syngeneic rats. The growth of tumors expressing IL-10 was substantially reduced compared to that of control tumors (p < 0.05). Intracranial tumors expressing IL-10 and IL-2 were established by co-implanting 9L-IL-10 cells with endothelial cells engineered to express IL-2. At 14 days post-implantation, tumors expressing IL-10 + IL-2 were 99% smaller than control-transfected tumors (p < 0.0001). This extent of anti-tumor effect could not be achieved by expression of IL-10 or IL-2 alone within tumors. Neither IL-10 nor a combination of IL-10 + IL-2 gene delivery inhibited tumor growth in severe combined immunodeficient (SCID-Beige) mice (p > 0.05). Immunohistochemical analysis revealed that IL-10 + IL-2 gene delivery markedly increased T-cell infiltration within the striatum ipsilateral to tumor cell implantation. These findings establish that IL-10 expression, particularly in combination with IL-2 expression, can have significant immune-dependent anti-tumor actions within intracranial gliomas.

B-lymphocyte proliferation during bovine leukemia virus-induced persistent lymphocytosis is enhanced by T-lymphocyte-derived interleukin-2

Bovine leukemia virus (BLV)-induced persistent lymphocytosis is characterized by a polyclonal expansion of CD5+ B lymphocytes. To examine the role of the cytokine microenvironment in this virus-induced B-lymphocyte expansion, the expression of interleukin-2 (IL-2), IL-4, IL-10, and gamma interferon (IFN-gamma) mRNA, was measured in stimulated peripheral blood mononuclear cells from persistently lymphocytotic BLV-infected cows, nonlymphocytotic BLV-infected cows, and uninfected cows. IL-2 and IL-10 mRNA expression and IL-2 functional activity were significantly increased when peripheral blood mononuclear cells from persistently lymphocytotic cows were stimulated with concanavalin A (ConA). Additionally, during persistent lymphocytosis, peak IL-2 and IL-10 mRNA expression was delayed, and elevated expression was prolonged. To determine the potential biologic importance of increased IL-2 and IL-10 expression, the response of isolated B lymphocytes from persistently lymphocytotic cows to human recombinant cytokines and to cytokine-containing supernatants from isolated T lymphocytes was examined. While recombinant human IL-10 (rhIL-10) did not consistently induce detectable changes, rhIL-2 increased viral protein (p24) and IL-2 receptor expression in isolated B lymphocytes from persistently lymphocytotic cows. Additionally, rhIL-2 and supernatant from ConA-stimulated T lymphocytes enhanced B-lymphocyte proliferation. The stimulatory activity of the T-lymphocyte supernatant could be completely inhibited with a polyclonal anti-rhIL-2 antibody. Finally, polyclonal anti-rhIL-2 antibody, as well as anti-BLV antibody, inhibited spontaneous proliferation of peripheral blood mononuclear cells from persistently lymphocytotic cows, demonstrating that the spontaneous lymphoproliferation characteristic of BLV-induced persistent lymphocytosis is IL-2 dependent and antigen dependent. Collectively, these findings strongly suggest that increased T-lymphocyte expression of IL-2 in BLV-infected cows contributes to development and/or maintenance of persistent B lymphocytosis.

Effect of B-cell receptor engagement on CD40-stimulated B cells

Activation of human B cells in vitro either by cross-linking of surface immunoglobulins (sIg) or by triggering CD40 antigen, in the presence of interleukin-10 (IL-10) and interleukin-2 (IL-2), may result in high levels of immunoglobulin secretion in vitro. We studied the combined effects of ligation of the B-cell receptor (BCR) and CD40 [with anti-CD40 monoclonal antibody (mAb)] on B-cell proliferation and production of human immunoglobulin. For this purpose highly purified splenic B cells were cultured with various combinations of anti-CD40 and IL-10/IL-2 or IL-4 in the presence of CD32-transfected L cells. Simultaneous cross-linking of the BCR was achieved by mAb held on CD32-L cells or Staphylococcus aureus (SA). We found that dual BCR and CD40 ligation with IL-10/IL-2 leads to reduced immunoglobulin G (IgG) secretion compared with B cells stimulated with either anti-CD40 and IL-10/IL-2, or compared with B cells stimulated with SA or anti-BCR mAb and IL-10/IL-2. Dual BCR and CD40 ligation with anti-immunoglobulin mAb (anti-kappa + anti-lambda light chains) but not with SA induced a similar reduction in IgM production. The reduced immunoglobulin secretion found during dual ligation is accompanied by increased proliferation. This was independent of cytokine stimulation but SA/CD40-induced proliferation was increased in the presence of IL-10/IL-2, although not with IL-4. The combination anti-kappa and anti-lambda with anti-CD40 showed a long-term suppression of IgG and IgM production (at least 14 days), while anti-kappa or anti-lambda alone, or SA, allowed a moderate recovery of immunoglobulin production by day 14. These results suggest that simultaneous B-cell antigen receptor cross-linking and CD40 engagement via CD40L on T cells induces strong initial proliferation. This may be followed later by antibody production depending on the strength of the BCR signal and the presence of the appropriate cytokines.

Cytokine messenger RNA expression in chronic inflammatory periodontal disease

It has previously been reported that, in periodontitis lesions, T cells with a memory/activated phenotype and with a type 2 cytokine profile accumulate in an oligoclonal fashion. Delineation of the role of cytokines in periodontal inflammation has, however, been complicated because of cross-regulation and because of their overlapping and often redundant effects. The aim of this study was to examine messenger RNA levels for interferon gamma, interleukin 4 (IL-4), IL-10, IL-12 and IL-13 in gingival tissues and peripheral blood mononuclear cells of patients with adult periodontitis. Reverse transcription polymerase chain reaction and subsequent image analysis was used to determine the level of mRNA for each cytokine. The mean expression of interferon gamma mRNA was significantly higher in peripheral blood mononuclear cells than in gingival tissues. In contrast, the mean expression of IL-10 mRNA was higher in gingival tissues than in peripheral blood mononuclear cells. This high expression of IL-10 mRNA was, in fact, seen in only 7 gingival tissue samples with the majority of samples showing levels similar to peripheral blood mononuclear cells. There was no difference in the mean expression of IL-12 p35 mRNA between gingival tissues and peripheral blood mononuclear cells. However, IL-12 p40 mRNA was expressed higher in gingival tissues than in peripheral blood mononuclear cells in 6 out of 16 samples with significant difference of mean expression. Like IL-10, gingival tissue samples and peripheral blood mononuclear cells expressed similar levels of IL-12 p40 mRNA. There was no difference in the mean expression of IL-13 in gingival tissues and peripheral blood mononuclear cells. Nevertheless, more peripheral blood mononuclear cell samples demonstrated high IL-13 mRNA expression than gingival tissue samples. IL-4 mRNA was weak but detectable in 3 gingival tissue samples. These results support the concept that cytokines form complex networks in periodontitis lesions and that their overlapping and redundant effects should be taken into account when considering the pathology of inflammatory periodontal disease. Dichotomous expression of IL-10 and IL-12 p40 mRNA in the periodontal lesion may be associated with disease entity.

The apoptosis and proliferation of SAC-activated B cells by IL-10 are associated with changes in Bcl-2, Bcl-xL, and Mcl-1 expression

Interleukin-10 (IL-10), a cytokine from mouse Th2 cells and macrophage that inhibits IL-2 and IFN-gamma production by Th1 cells, has been reported to stimulate growth and differentiation of B cells activated by CD40 or antigen receptor crosslinking. Our early observation revealed that IL-10 had B cell growth factor (BCGF) activity in human B cells preactivated with SAC or anti-Ig. The responsiveness of the preactivated B cells to IL-10 greatly increased when B cells were activated in the presence of IL-2, whereas IL-10 has no BCGF activity when added at the initiation of activation by SAC. To investigate the dual effects (proliferation and apoptosis) of IL-10 on B cells, the expression of a panel of bcl-2 protoncogene family members, bcl-2, bcl-x, mcl-1, and bax, was analyzed when B cells were activated by SAC. Bcl-xL protein was not expressed in the small resting B cells but was induced by SAC stimulation, reaching its peak at 48 hr. The addition of IL-2 further augmented the Bcl-xL expression with the same kinetics, whereas Bcl-2 and Mcl-1 were expressed by resting B cells and enhanced by SAC stimulation. However, the addition of IL-10 at the initiation of activation down-regulated Bcl-xL, Bcl-2, and Mcl-1 expression. At the same time, B cell proliferation was inhibited and apoptotic cell number increased, suggesting the growth arrest and/or apoptosis of B cells. The apoptosis of SAC-activated B cells by IL-10 was further confirmed by propidium iodide-staining and Annexin V-FITC-staining methods. In contrast, IL-10 failed to down-regulate the Bcl-xL and Bcl-2 expression but rather augmented the expression of Mcl-1 of B cells after preactivation for 48 hr with SAC and IL-2. Under this culture condition, B cells responded to IL-10 to proliferate and differentiate, while IL-2 and IL-10 had an additive or synergistic effect. Taken together, our data suggest that IL-10 acts on the induction stage of Bcl-xL expression and regulates the apoptosis and proliferation of SAC-activated B cells through their bcl-2 family gene expression.

Interferon beta induces interleukin-10 expression: relevance to multiple sclerosis

Interferon-beta decreases the relapse rate, relapse severity, progression of neurological disability, and development of new brain lesions observed with brain magnetic resonance imaging in relapsing-remitting multiple sclerosis patients. The mechanism of action of this effect is presently unknown. This study was based on the hypothesis that immunoregulatory effects of interferon-beta may underlie its demonstrated clinical efficacy. The objective of the study was to determine the effect of interferon-beta-1a on the expression of interleukin-10, a cytokine that strongly inhibits cell-mediated immune responses. Interferon-beta-1a induced accumulation of interleukin-10 messenger RNA and protein secretion by cultured peripheral blood mononuclear cells. The observed in vitro effects were similar for healthy control subjects and multiple sclerosis patients. Intramuscular injections of interferon-beta-1a increased serum levels of interleukin-10 at 12 and 24 hours following the injection. Greater increases were induced with 12 x 10(6)-IU than 6 x 10(6)-IU injections. The effect of interferon-beta-1a was relatively specific for interleukin-10, as treatment with interferon-beta-1a did not result in accumulation of transforming growth factor-beta messenger RNA. Upregulation of interleukin-10 represents a possible mechanism of action of interferon-beta's therapeutic effect in relapsing-remitting multiple sclerosis, and has implications for therapy of other autoimmune diseases.

Role of interleukin-2 and interferon-gamma in inducing production of IgG subclasses in lymphocytes of human newborns

Unlike lymphocytes from adults, lymphocytes from cord blood of neonates cannot synthesize immunoglobulin G (IgG) in response to pokeweed mitogen (PWM). By using this mitogen in concert with interferon-gamma (IFN-gamma), interleukin-2 (IL-2), or interleukin-6 (IL-6), we studied the induction of IgG subclass molecules in lymphocytes of human neonates. IFN-gamma induced a limited, but substantial, enhancement of IgG2 production by neonatal lymphocytes. IL-2 dose dependently increased the production of each neonatal IgG subclass, whereas IL-6 did not. However, in adult lymphocytes, and under specific conditions, IL-6 or IL-2 each increased the production of all four IgG subclasses. Early in the culture IFN-gamma synergized with IL-2 during the latter or whole culture period to enhance cord blood IgG2 levels. This finding contrasted with the adult IgG2 synthesis synergistically up-regulated by IFN-gamma and IL-6. IL-2 caused a graded increase in immunoglobulin production in neonatal lymphocytes with IgG3 being the highest and IgG2 the lowest, thus corresponding to the differential increase of serum levels of IgG3/IgG1 and IgG4/IgG2 early in childhood. Results suggest that IL-2, but not IL-6, is critical to the development of human IgG subclass production.